<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
    
    }

    .box {
      width: 1198px;
      height: 460px;
      background-color: gray;
      margin: 0 auto;
    }
    .left {
      width: 30%;
      height: 460px;
      float: left;
      background-color: green;
    }
    .right {
      width: 70%;
      height: 460px;
      float: left;
      background-color: honeydew;
    }
  </style>
</head>
<body>
  <div class="box">
    <div class="left">左侧</div>
    <div class="right">右侧</div>
  </div>
</body>
</html>